MouseEvents with Bitmap objects

I am trying to have a mouse event register when the cursor leaves an image, but the listener function never gets entered. In AS3, how does one get the MouseOver event to work for a bitmap like I have?

public class MyClass extends MovieClip {
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[Embed(source=‘orange.jpg’)]
public var MyOrange:Class;
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public function MyFunction() {
var graphix1:Bitmap = new MyOrange();
graphix1.x = 70;
graphix1.y = 124;
graphix1.addEventListener(MouseEvent.MOUSE_OVER, showOrange);
}